The theory began with the cold-war Soviet hoax document US Army Field Manual 30-31B where the term first appeared. It was made more broadly dispersed by an Italian parliamentary committee, and later popularized by Daniele Ganser a Swiss academic.

The term "strategy of tension" recurred during the trials that followed in the 1970s and 1980s Years of Lead ("anni di piombo"), during which terror attacks and assassinations were committed by apparently neofascist terrorists related to the Operation Gladio.[citation needed]

It was primarily members and international supporters of the Italian Communist Party who invented and popularized the term "strategy of tension". They meant to draw attention to the crimes of the Italian Right and Far-Right parties who were allegedly supported by the foreign belligerents.[citation needed]

A 1995 report from the Left Democrats (the rebranded Communist Party of Italy, PCI) to a subcommittee of the Italian Parliament first stated that a "strategy of tension" was followed by Gladio and had been supported by the United States to "stop the PCI, and to a certain degree also the PSI, from reaching executive power in the country". Members of the Democratic Party of the Left (PDS)(the rebranded Communist Party of Italy, PCI), part of the Commission on Terrorism headed by senator Giovanni Pellegrino and created in 1988, also described the Italian peninsula since the end of World War II as a "country with 'limited sovereignty'" and as an "American colony" The centrist Italian Republican party described the claims as worthy of a 1970s Maoistgroup. Aldo Giannuli, a historian who works as a consultant to the parliamentary terrorism commission, sees the release of the Left Democrats' report as a manoeuvre dictated primarily by domestic political considerations. "Since they have been in power the Left Democrats have given us very little help in gaining access to security service archives," he said. "This is a falsely courageous report."

General Gianadelio Maletti, commander of the counter-intelligence section of the Italian military intelligence service from 1971 to 1975, stated that his men in the region of Venice discovered a rightwing terrorist cell that was supplied military explosives from Germany, and he alleged that US intelligence services instigated and abetted rightwing terrorism in Italy during the 1970s.[2]..